Like many American cities, Memphis, Tennessee, has a long history of vexed relationships between the police and Black citizens. Also like many cities, it has seen an increase in activism for police reform in recent years. But over the past two years, as I reported on policing in Memphis, I heard laments from activists that they struggled to bring the attention of elected officials and a broad swath of citizens to the problems they saw.The lack of attention may no longer be an issue—at least for now.Earlier this month, 29-year-old Tyre Nichols died after an encounter with officers near his...